How to change radio centre frequency

HTT · December 2, 2021, 12:24am

I want to change radio_1 of my RAK831 (AS923) from 924600000 to 922600000:

chirpstack-concentratord-sx1301[1784]: Configuring radio, radio: 0, enabled: true, center_freq: 923600000, type: SX1257
chirpstack-concentratord-sx1301[1784]: Configuring radio, radio: 1, enabled: true, center_freq: 924600000, type: SX1257

How can I do that, thanks!

brocaar · December 16, 2021, 10:46am

The Concentratord configures the center-frequencies based on the channels that you configure. See for example:

github.com

brocaar/chirpstack-concentratord/blob/master/chirpstack-concentratord-sx1301/src/config/helpers.rs

const DEFAULT_RADIO_BANDWIDTH: u32 = 925000;

struct ChannelConfiguration {
    pub freq_hz: u32,
    pub bandwidth: u32,
}

impl ChannelConfiguration {
    fn min_radio_freq(&self) -> u32 {
        let radio_bw = get_radio_bandwidth(self.bandwidth);
        return self.freq_hz - (self.bandwidth / 2) + (radio_bw / 2);
    }
}

fn get_radio_bandwidth(channel_bw: u32) -> u32 {
    match channel_bw {
        500000 => 1100000,
        250000 => 1000000,
        125000 => 925000,
        _ => DEFAULT_RADIO_BANDWIDTH,

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